Catalase Content in Peanut Milk as Affected by Growth of Aspergillus parasiticus.

Changes in catalase content and pH of peanut milk in which Aspergillus parasiticus was cultured were monitored over a 10-d period at 30°C. A 3- to 10-fold increase in catalase content was detected after 6 d of incubation, while the content in uninoculated (control) peanut milk decreased by about 50% after 3 d of incubation. The pH of uninoculated catalase-supplemented peanut milk increased from 6.7 to 9.2, whereas the pH of inoculated peanut milk remained essentially unchanged. Production of catalase by A. parasiticus and perhaps other molds could be a basis for developing a hydrogen peroxide treatment for separating mold-contaminated kernels from sound kernels.

Separation of Aflatoxin-Contaminated Kernels from Sound Kernels by Hydrogen Peroxide Treatment.

Blends (0:1, 1:3, 1:1, and 3:1, wt/wt) of aflatoxin-contaminated and sound peanut kernels were submerged for 1, 2, and 3 min in various concentrations of hydrogen peroxide solution. The effectiveness of these treatments in separating aflatoxin-contaminated kernels from sound kernels was determined. Peanuts that floated (floaters) and those that did not (sinkers) were subjected to aflatoxin analysis. Second order polynomial equations were satisfactorily fitted to the experimental data. Hydrogen peroxide concentrations of 0.075, 0.150, and 0.25% resulted in a reduction in aflatoxin content in the kernels in the sinker fraction by 90% within 1 min, regardless of the initial aflatoxin content. The total aflatoxin content in sinker and floater fractions was approximately the same as that in unfractionated samples, indicating that the low concentrations of hydrogen peroxide in treatment solutions did not degrade aflatoxin. Response surface methodology was used to generate contour plots which revealed optimum treatment conditions for giving a maximum yield of the sinker fraction with low aflatoxin content. For peanuts containing 50 ppb aflatoxin, optimum conditions consist of a 0.08% hydrogen peroxide treatment for 0.7 min. This procedure results in a maximum sinker fraction yield of 85.5% of the original lot with a residual aflatoxin content of ≤5 ppb.